PROJECT SUMMARY Though often educated in mainstream classrooms, children with mild-to-moderate sensorineural hearing loss are at significantly greater risk for poor social and academic outcomes than their peers with normal hearing. Poor outcomes in children with hearing loss are often attributed to their impaired speech understanding. Specifically, the acoustic signal containing speech is poorly represented in the impaired peripheral auditory system of children with hearing loss, and the background noise and reverberation present in classrooms further degrades this representation. Common interventions, such as the use of hearing aids and classroom- based assistive listening devices, increase the audibility of speech, but often fail to result in commensurate benefits for children with hearing loss. A potential reason for this is that children's ability to understand speech in complex acoustic environments is not only dependent on the audibility of speech, but also on their ability to selectively attend to the target speech stream, such as their teacher's voice, while ignoring irrelevant sounds in the environment, such as their classmates' conversations. This ability requires auditory selective attention, a cognitive process known to develop throughout childhood and expected to be impaired in children with hearing loss. It remains unknown, however, whether auditory selective attention is impaired in children with hearing loss and, if so, how this contributes to their poor social and academic outcomes. The objective of this project is to investigate how hearing loss during childhood impairs auditory selective attention, and to quantify the implications of this for speech recognition in complex acoustic environments. The experiments are designed to directly measure selective attention in the auditory and visual domains using a series of change detection tasks (Aim 1) and to investigate the role of auditory selective attention during speech recognition in the presence of background noise and reverberation (Aim 2). In order to explore how hearing loss and age contribute to these relations, this performance will be measured in children with normal hearing and mild-to-moderate hearing loss who represent the range of elementary-school ages. Additionally, standardized measures of language ability and executive function will be included in order to employ multiple regression analyses to test whether individual differences in auditory selective attention account for variability in speech recognition in complex acoustic environments. Findings from this research will advance current understanding of the relation between age, hearing loss, auditory selective attention, and speech recognition during childhood. This knowledge will inform intervention strategies to promote the development of auditory selective attention in children with hearing loss who are not receiving commensurate benefits from the use of hearing aids or classroom-based assistive listening devices. Ultimately, the outcomes of this research will help maximize the social and academic success of children with hearing loss in mainstream classrooms.